Qualitative index of fibrosis distribution in AF and SR
In order to correlate location of LVA between AF and SR maps, a qualitative index was defined based on 4 projections (antero-posterior (AP), postero-anterior (PA), superior (SUP) and inferior (INF)). In every view, LVA in SR and AF were compared, assigning different values ​​according to the degree of similarity. In this way, a value of 0 would correspond to discrepancies in the location of LVA between both maps; if LVA were located in the same zones, the assigned value would be 2. For cases where there were no LVA in SR and therefore the comparison was not possible, the assigned value would be 1. Finally, values ​​obtained for each projection were added, obtaining a final value. If this value was equal to or greater than 5 (which means that at least one projection coincides and the other 3 are not evaluable), it was defined as correspondence between LVA in both maps. This process was performed for both thresholds, 0.5 and 0.3 mV.